package com.ibm.finance.tools.wwcet.util.hdsc;

import java.lang.*;
import java.sql.Connection;
import java.util.List;

import javax.sql.DataSource;

import org.apache.log4j.Logger;

/**
 * This class is database data exporter that can export matched records for configured database tables with optional records purge and/or zipping of export file. It's assumed that this class will be initialized with Spring setter dependency injection only. It uses injected DataSource instance and JDBC to access the database by executing prepared statements and calling stored procedures. The configuration for this class is mostly represented with a list of DBTableExportParameters instances. DBDataExporter performs logging of errors and debug information with use of Log4j logger. This class can export data from DB2 databases running on the same machine where the JVM is running only. It uses DB2-specific EXPORT admin command for this.
 * 
 * Thread Safety:
 * This class is mutable, but assuming that its initialization is performed with Spring only, its mutable fields are never changed after initialization. It's assumed that a transaction with SERIALIZABLE isolation level must be configured for export() method in Spring application context for the configured DataSource instance. This assumption guarantees thread safety for this class since export operation will never be performed by two threads or applications for the same database at a time.
 */
public class DBDataExporter {
    /**
     * The Log4j logger to be used by this class for logging errors and debug information. Is initialized during class loading and never changed after that. Cannot be null. Is used in export(), logMessages() and compressFile() methods.
     * See section 1.3.1 of CS for logging requirements.
     */
    private static final Logger LOGGER = Logger.getLogger(DBDataExporter.class);

    /**
     * The data source to be used for establishing a database connection. Is initialized via Spring setter injection. Cannot be null after initialization (note that actual check is performed in checkInit() method). Has a setter. Is used in export().
     */
    private DataSource dataSource;

    /**
     * The list of exporting parameters for database tables. Is initialized via Spring setter injection. Cannot be null/empty, cannot contain null after initialization (note that actual check is performed in checkInit() method). Has a setter. Is used in export().
     */
    private List<DBTableExportParameters> tableExportParameters;

    /**
     * Creates an instance of DBDataExporter.
     * 
     * Implementation Notes:
     * Do nothing.
     */
    public DBDataExporter() {
    }

    /**
     * Checks whether this class was initialized by Spring properly. It must be configured as "init-method" in Spring bean configuration.
     * 
     * Throws:
     * DBDataExporterInitializationException if the class was not initialized properly (e.g. when required properly is not specified or property value has invalid format)
     * 
     * Implementation Notes:
     * 1. If dataSource == null then throw DBDataExporterInitializationException.
     * 2. If tableExportParameters == null then throw DBDataExporterInitializationException.
     * 3. If tableExportParameters.isEmpty() then throw DBDataExporterInitializationException.
     * 4. If tableExportParameters contains null then throw DBDataExporterInitializationException.
     * @throws DBDataExporterInitializationException if the class was not initialized properly (e.g. when required properly is not specified or property value has invalid format)
     */
    protected void checkInit() {
    }

    /**
     * Performs the export operation. For each configured table this method executes "EXPORT" DB2 command, and then optionally deletes exported records from DB and/or compresses the export file.
     * 
     * Returns:
     * the total number of exported records (for all tables)
     * 
     * Throws:
     * DBDataExportingDatabaseException if some error occurred when accessing the database
     * DBDataExportingException if some other error occurred
     * 
     * Implementation Notes:
     * 1. Get the database connection:
     *      Connection connection = DataSourceUtils.doGetConnection(dataSource);
     * 2. int totalExportedRecordsNum = 0;
     * 3. For each params from tableExportParameters do:
     *      3.1. Get the table export start time:
     *              exportStartTime = new Date();
     *      3.2. Get records select criteria from database table export parameters:
     *              String selectCriteria = params.getSelectCriteria();
     *      3.3. String whereClause = " WHERE" + selectCriteria;
     *      3.4. Create string builder for DB2 command:
     *              commandBuilder = new StringBuilder();
     *      3.5. Get export file path template to construct export file path:
     *              String exportFilePath = params.getExportFilePathTemplate();
     *      3.6. For each occurrence of "%TIMESTAMP:format%" in exportFilePath (use regular expression pattern: format is any string that doesn't contain '%') do:
     *              3.6.1. Extract format:String from the template field.
     *              3.6.2. Replace this occurrence of "%TIMESTAMP:format%" in exportFilePath with the value of new SimpleDateFormat(format).format(exportStartTime).
     *      3.7. Create File instance for export file:
     *              exportFile = new File(exportFilePath);
     *      3.8. Convert relative export file path to an absolute one:
     *              exportFilePath = exportFile.getAbsolutePath();
     *      3.9. Create export file directory if doesn't exist:
     *              exportFile.getParentFile().mkdirs();
     *      3.10. If not exportFile.getParentFile().isDirectory() then throw DBDataExportingException.
     *      3.11. Get export file format from the table export parameters:
     *                ExportFileFormat format = params.getFormat();
     *      3.12. Append beginning of the export command SQL:
     *                commandBuilder.append("EXPORT TO \"" + exportFilePath + "\" OF " + format.toString());
     *      3.13. If format != ExportFileFormat.WSF then
     *                3.13.1. Create string builder for file type modifier options:
     *                              modifierBuilder = new StringBuilder();
     *                3.13.2. Get code page from the table export parameters:
     *                              String codePage = params.getCodePage();
     *                3.13.3. If codePage != null then
     *                              3.13.3.1. Append codepage modifier:
     *                                               modifierBuilder.append(" CODEPAGE=" + codePage);
     *                3.13.4. If format == ExportFileFormat.DEL then
     *                              3.13.4.1. Get column separator from the table export parameters:
     *                                               String columnSeparator = params.getColumnSeparator();                    3.13.4.2. If columnSeparator != null then
     *                                               3.13.4.2.1. Append column separator modifier:
     *                                                                   modifierBuilder.append(" COLDEL" + escapeSeparator(columnSeparator));
     *                              3.13.4.3. Get string delimiter from the table export parameters:
     *                                               String stringDelimiter = params.getStringDelimiter();
     *                              3.13.4.4. If stringDelimiter != null then
     *                                               3.13.4.4.1. Append character string delimiter modifier:
     *                                                                   modifierBuilder.append(" CHARDEL" + escapeSeparator(stringDelimiter));
     *                              3.13.4.5. Get timestamp format from the table export parameters:
     *                                               String timestampFormat = params.getTimestampFormat();
     *                              3.13.4.6. If timestampFormat != null then
     *                                               3.13.4.6.1. Append timestamp format modifier:
     *                                                                   modifierBuilder.append(" TIMESTAMPFORMAT=\"" + timestampFormat + "\"");
     *                              3.13.4.7. Get decimal point character from the table export parameters:
     *                                               String decimalPoint = params.getDecimalPoint();
     *                              3.13.4.8. If decimalPoint != null then
     *                                               3.13.4.8.1. Append decimal point modifier:
     *                                                                   modifierBuilder.append(" DECPT" + escapeSeparator(decimalPoint));
     *                              3.13.4.9. Get leading zero stripped flag from the table export parameters:
     *                                               boolean leadingZeroStripped = params.isLeadingZeroStripped();
     *                              3.13.4.10. If leadingZeroStripped then
     *                                                 3.13.4.10.1. Append leading zero stripped modifier:
     *                                                                        modifierBuilder.append(" STRIPLZEROS");
     *                              3.13.4.11. Get plus sign removed flag from the table export parameters:
     *                                                 boolean plusSignRemoved = params.isPlusSignRemoved();
     *                              3.13.4.12. If plusSignRemoved then
     *                                                 3.13.4.12.1. Append plus sign removed modifier:
     *                                                                        modifierBuilder.append(" DECPLUSBLANK");
     *                3.13.5. Get modifier options as string:
     *                              String modifierOptions = modifierBuilder.toString();
     *                3.13.6. If modifierOptions is not empty then
     *                              3.13.6.1. Append file type modifier options to the command:
     *                                               commandBuilder.append(" MODIFIED BY" + modifierOptions);
     * 
     *      3.14. Indicate that export messages should be saved by database:
     *                commandBuilder.append(" MESSAGES ON SERVER");
     *      3.15. Get table name from database table export parameters:
     *                String tableName = params.getTableName();
     *      3.16. Append the beginning of SELECT query:
     *                commandBuilder.append(" SELECT * FROM " + tableName + whereClause);
     * 
     *      3.17. Get command as string:
     *                String command = commandBuilder.toString();
     *      3.18. Prepare a DB2 command call:
     *                CallableStatement callableStatement = connection.prepareCall("CALL SYSPROC.ADMIN_CMD(?)");
     *      3.19. Set command as SP parameter:
     *                callableStatement.setString(1, command);
     *      3.20. Execute the command:
     *                callableStatement.execute();
     *      3.21. Get the result set:
     *                ResultSet resultSet = callableStatement.getResultSet();
     *      3.22. If not resultSet.next() then throw DBDataExportingException.
     *      3.23. Get the number of exported messages:
     *                int rowsExported = resultSet.getInt(1);
     *      3.24. totalExportedRecordsNum += rowsExported;
     *      3.25. Get SQL to be used for retrieving messages with export details:
     *                String getMessagesSql = resultSet.getString(2);
     *      3.26. Get SQL to be used for removing export details messages:
     *                String removeMessagesSql = resultSet.getString(3);
     *      3.27. Retrieve, log and remove the export details messages:
     *                logMessages(connection, getMessagesSql, removeMessagesSql);
     * 
     *      3.28. Get the purge required flag from the table export parameters:
     *                boolean purgeRequired = params.isPurgeRequired();
     *      3.29. If purgeRequired then
     *                3.29.1. Prepare statement for removing exported records:
     *                              PreparedStatement preparedStatement = connection.prepareStatement("DELETE FROM " + tableName + whereClause);
     *                3.29.2. Execute the statement:
     *                              int rowsDeleted = preparedStatement.execute();
     *                3.29.3. If rowsDeleted != rowsExported then throw DBDataExportingException.
     * 
     *      3.30. Get compression required flag from the table export parameters:
     *                boolean zipRequired = params.isZipRequired();
     *      3.31. If zipRequired then
     *                3.31.1. Compress and delete the export file:
     *                              compressFile(exportFilePath);
     *      3.32. Log (new Date().getTime() - exportStartTime.getTime()) together with tableName and rowsExported at INFO level.
     * 
     * 4. Releases the connection:
     *      DataSourceUtils.doReleaseConnection(connection, dataSource);
     * 5. Return totalExportedRecordsNum.
     * 
     * Note: statements and result sets must be properly closed.
     * Note: DBDataExportingDatabaseException should be used for wrapping SQLException. errorCode and sqlState properties of DBDataExportingDatabaseException must be initialized with the values of the namesake properties of SQLException.
     * @throws DBDataExportingDatabaseException if some error occurred when accessing the database
     * @throws DBDataExportingException if some other error occurred
     * @return the total number of exported records (for all tables)
     */
    public int export() {
        return 0;
    }

    /**
     * Compresses the given file to a ZIP file.
     * 
     * Parameters:
     * filePath - the path of the file to be compressed
     * 
     * Throws:
     * DBDataExportingException if some error occurred
     * 
     * Implementation Notes:
     * 1. Create a File instance for the input file:
     *      inputFile = new File(filePath);
     * 2. Create output file stream:
     *      outputFileStream = new FileOutputStream(filePath + ".zip");
     * 3. Create zip output stream:
     *      zipOutputStream = new ZipOutputStream(outputFileStream);
     * 4. Create input file stream:
     *      inputFileStream = new FileInputStream(inputFile);
     * 5. Get short file name:
     *      String fileName = inputFile.getName();
     * 6. Create ZIP entry:
     *      zipEntry = new ZipEntry(fileName);
     * 7. Put next entry to the ZIP file:
     *      zipOutputStream.putNextEntry(zipEntry);
     * 8. Create a byte buffer array:
     *      byte[] buf = new byte[65536];
     * 9. int len;
     * 10. While ((len = inputFileStream.read(buf)) > 0) do:
     *        10.1. Write read data to the ZIP stream:
     *                  zipOutputStream.write(buf, 0, len);
     * 11. Close the input file:
     *        inputFileStream.close();
     * 12. Close the ZIP entry:
     *        zipOutputStream.closeEntry();
     * 13. Close the ZIP stream:
     *        zipOutputStream.close();
     * 14. Delete the input file:
     *        boolean deleted = inputFile.delete();
     * 15. If not deleted then log a warning message.
     * @throws DBDataExportingException if some error occurred
     * @param filePath the path of the file to be compressed
     */
    private static void compressFile(String filePath) {
    }

    /**
     * Logs the DB2 database messages that can be retrieved and removed with the given SQL statements.
     * Details about the provided SQL statements can be found here (section "Result set information"): http://publib.boulder.ibm.com/infocenter/db2luw/v9/index.jsp?topic=/com.ibm.db2.udb.admin.doc/doc/r0023573.htm
     * 
     * Parameters:
     * connection - the connection to be used
     * getMessagesSql - the SQL query string to be used for retrieving messages
     * removeMessagesSql - the SQL statement for removing messages from the database
     * 
     * Throws:
     * DBDataExportingDatabaseException if some error occurred when retrieving or removing the database messages
     * 
     * Implementation Notes:
     * 1. Prepare statement for retrieving messages from DB:
     *      PreparedStatement preparedStatement = connection.prepareStatement(getMessagesSql);
     * 2. Execute query:
     *      ResultSet resultSet = preparedStatement.executeQuery();
     * 3. While resultSet.next() do:
     *      3.1. Get the SQL code:
     *              String sqlCode = resultSet.getString(1);
     *      3.2. Get the error message:
     *              String message = resultSet.getString(2);
     *      3.3. Log sqlCode and message at INFO level.
     * 4. Prepare a statement for removing the messages:
     *      CallableStatement callableStatement = connection.prepareCall(removeMessagesSql);
     * 5. Execute the statement:
     *      callableStatement.execute();
     * 
     * Note: result set and statements must be properly closed.
     * Note: DBDataExportingDatabaseException should be used for wrapping SQLException. errorCode and sqlState properties of DBDataExportingDatabaseException must be initialized with the values of the namesake properties of SQLException.
     * @throws DBDataExportingDatabaseException if some error occurred when retrieving or removing the database messages
     * @param connection the connection to be used
     * @param getMessagesSql the SQL query string to be used for retrieving messages
     * @param removeMessagesSql the SQL statement for removing messages from the database
     */
    private static void logMessages(Connection connection, String getMessagesSql, String removeMessagesSql) {
    }

    /**
     * Escapes the specified separator to be used as a option modifier value in DB2 command. To do this it's required to double single and double quote characters only.
     * 
     * Parameters:
     * separator - the separator (a single character or string in format "0xDD", where D represents a HEX digit, case insensitive)
     * 
     * Returns:
     * the escaped separator value (not null, not empty)
     * 
     * Implementation Notes:
     * 1. If separator equals to one of "\"" and "'" then
     *      1.1. Return separator + separator.
     * 2. Return separator.
     * @param separator the separator (a single character or string in format "0xDD", where D represents a HEX digit, case insensitive)
     * @return the escaped separator value (not null, not empty)
     */
    private static String escapeSeparator(String separator) {
        return null;
    }

    /**
     * Sets the data source to be used for establishing a database connection.
     * 
     * Parameters:
     * dataSource - the data source to be used for establishing a database connection
     * @param dataSource the data source to be used for establishing a database connection
     */
    public void setDataSource(DataSource dataSource) {
    }

    /**
     * Sets the list of exporting parameters for database tables.
     * 
     * Parameters:
     * tableExportParameters - the list of exporting parameters for database tables
     * @param tableExportParameters the list of exporting parameters for database tables
     */
    public void setTableExportParameters(List<DBTableExportParameters> tableExportParameters) {
    }
}

